Decrypt given data previously encoded with seed-cfb cipher algo. SEED in CFB (Cipher Feedback) mode, converting the block cipher into a stream cipher. CFB mode was introduced for SEED to handle streams of data more effectively while maintaining the security of the algorithm. SEED-CFB is secure but slower than modern alternatives like AES. Our decryption process assumes the IV string is prepended in the encoded string during the encryption process. You can not decrypt and get the correct results if the IV or passphrase mismatch occurs between encryption and decryption process.